Anchor device for use with catheters

ABSTRACT

An anchor device to simplify catheterization procedures, particularly for insertion and maneuvering of large catheters in tortuous arteries, vessels, or other lumen is disclosed. In some embodiments, the anchor device includes an anchor stent formed from a plurality of zig-zag shaped wire elements that are coupled together. The device further includes a plurality of connector struts attached at a proximal end of the anchor stent, the connector struts coalescing to form a strut tip. A guide device, such as a guidewire, is attached to the anchor stent at the strut tip and may be used to guide the anchor stent into the arteries or other vessels and toward a target treatment site.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.14/959,847, filed Dec. 4, 2015, which is a nonprovisional of and claimsthe benefit under 35 U.S.C. §119(e) of U.S. Provisional PatentApplication No. 62/088,382, filed Dec. 5, 2014, each of which is herebyincorporated by reference herein in its entirety.

TECHNICAL FIELD

The field of the present disclosure relates generally to medicaldevices, and in particular, to anchor devices that may be used toadvance large catheters within tortuous vascular or non-vascularanatomy.

BACKGROUND

In the medical industry, it is customary to use catheters that extendinto arteries, vessels, or other lumen of a patient's body to introduceor remove liquids, particles, or other substances into or out of thepatient's body, or to support other suitable treatment procedures.Controlled placement of catheters is important in many facets of themedical field. For example, drug delivery catheters provide a means fordelivering concentrated drugs or other substances to a specific site tomaximize the therapeutic effect, while minimizing side effects that mayoccur from receiving drugs orally or intravenously.

In some procedures, it may be necessary to advance a large catheterwithin tortuous vascular and non-vascular tubular anatomy to reach atarget site. Typically, such procedures may require medical personnel toimpart greater force to maneuver the catheter within the tortuousvessel. In such procedures, it is important to gauge the insertion forceof the catheter properly to avoid inserting the catheter farther thananticipated, which may lead to unintended complications or may make itdifficult to provide treatment to the target site. In addition, it isalso important that catheters are firmly secured once positioned in thelumen, and that the catheters remain in the desired position despite thepatient's movement or other factors that may disturb the position of thecatheter to avoid causing potential trauma by the unexpected removal ofthe catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example anchor device according to one embodiment.

FIGS. 2 and 3 illustrate an example use of a multi-axial catheter systemwith the anchor device of FIG. 1 according to one embodiment.

FIG. 4 illustrates an embodiment of an anchor stent with a distal endfitted with a porous barrier.

FIG. 5 illustrates another embodiment of an anchor stent with a distalend fitted with a nonporous barrier.

FIG. 6 illustrates an example of an anchor device with an anchor stenthaving varying thickness profiles in accordance with one embodiment.

FIGS. 7 and 8 illustrate an example use of a catheter with the anchordevice of FIG. 6 in accordance with one embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

With reference to the drawings, this section describes particularembodiments and their detailed construction and operation. Theembodiments described herein are set forth by way of illustration onlyand not limitation. The described features, structures, characteristics,and methods of operation may be combined in any suitable manner in oneor more embodiments. In view of the disclosure herein, those skilled inthe art will recognize that the various embodiments can be practicedwithout one or more of the specific details or with other methods,components, materials, or the like. For the sake of clarity andconciseness, certain aspects of components or steps of certainembodiments are presented without undue detail where such detail wouldbe apparent to those skilled in the art in light of the teachings hereinand/or where such detail would obfuscate an understanding of morepertinent aspects of the embodiments.

The present inventor has recognized a need for an anchor device havingan improved design to simplify catheterization procedures. As is furtherdescribed below, certain embodiments disclosed herein may be capable ofachieving various advantages, including one or more of the following:(1) providing an anchor device with a streamlined design to simplifyendovascular introduction and decrease forces required to positiondelivery catheters at desired sites; (2) providing such an anchor devicesuitable to aid in advancing large catheters within tortuous vascular(and non-vascular tubular) anatomy; and (3) providing such an anchordevice capable of securing the catheter in position to minimize the riskof dislodgment. Additional aspects and advantages will be apparent fromthe following detailed description of example embodiments, whichproceeds with reference to the accompanying drawings.

Collectively, FIGS. 1-8 illustrate various embodiments of an anchordevice 10, 50, 60 that may be employed endovascularly and used inconjunction with delivery catheters for a variety of medical procedures,such as for stroke thrombectomy or drug delivery purposes. With generalreference to FIG. 1, the anchor device 10 is a generally tubular deviceincluding an anchor stent 100 formed of a plurality of wire elements105, where each individual wire element 105 is shaped in a zig-zagpattern and coupled to adjacent wire elements. As is further describedwith reference to FIGS. 1-3, the anchor device 10 may be used as a meansto provide a distal anchor point for a guide wire 135 to aid in theadvancement of large catheters within tortuous vascular (andnon-vascular tubular) anatomy 155.

In other embodiments, the anchor device 10, or a miniaturized versionthereof, may be used to allow intracranial catheter exchanges withgreater stability and much lower risk of vessel perforations. In anotherembodiment, the anchor device 10, or a larger version thereof, may beuseful for catheter exchanges in large vessels like the aorta orpulmonary arteries, such as during aortic aneurysm stent-graftinsertions. In still other embodiments, the anchor device 10 may beuseful in non-vascular catheter interventions, such as in the biliarytree, ureters, and tracheobronchial tree, or may be useful as ananchor-filter or as an access aid during carotid stenting, or may beuseful as an embolic device. Additional details of these and otherembodiments are further described in detail below with reference to thefigures.

With particular reference to FIG. 1, the following sections describeadditional details of the anchor device 10 and the components thereof.As briefly described previously, the anchor device 10 includes aplurality of wire elements 105 coupled together to form an anchor stent100, which is a generally tubular-shaped, self-expanding mesh structure.In some embodiments, the wire elements 105 may be coupled together, suchas via a welding process, to create a “closed-cell” design withsufficient rigidity to allow the anchor stent 100 to move throughtortuous vessel 155 (see FIGS. 2 and 3). For example, with generalreference to FIG. 1, adjoining wire elements 105 a and 105 b may bewelded at every junction 110 where respective ends 115, 120 of theadjoining wire elements 105 a, 105 b meet. In this configuration, theanchor stent 100 is afforded sufficient rigidity to move through thetortuous vessel 155 as further described below with reference to FIGS.2-3. The diameter of the anchor stent 100 may vary depending upon thesize of the vessel or tubular body structure in which the anchor device10 is to be used. In various embodiments, the anchor stent 100 may beprovided in a variety of fully expanded diameters ranging from 2 mm upto 30 mm. In other embodiments, the anchor stent 100 may be larger than30 mm.

As described previously, the anchor stent 100 may have a “closed-cell”design. However, in other embodiments, the anchor stent 100 may insteadhave a more “open-cell” design so that the anchor stent 100 is capableof following sharp curves without kinking. For example, in oneembodiment, the adjoining wire elements 105 a, 105 b may instead bewelded at alternating junctions, thereby creating an anchor stent 100with some welded ends, but leaving some ends not welded or otherwiseattached to one another. In this configuration, the staggered weldsbetween the adjacent wire elements 105 a, 105 b may help impart greaterflexibility to the anchor stent 100 without sacrificing overallstability.

In some embodiments, the wire elements 105 may be composed of a metallicmaterial exhibiting shape memory/superelasticity qualities, such asnitinol (a nickel-titanium alloy), Elgiloy (a cobalt, chromium, andnicket based alloy) or other suitable shape-memory alloys.Alternatively, in other embodiments, the wire elements 105 may becomposed of other suitable materials, including non-metallic materials,capable of creating the tubular stent structure. In still otherembodiments, the wire elements 105 may be composed of a stiffer metallicmaterial to provide greater rigidity and stiffness to the anchor device100. Depending on the requirements of the clinical situation and/orother factors, the anchor stent 100 may be made of different materialsto provide suitable degrees of stiffness as may be necessary.

With reference to FIG. 1, a proximal end 125 of the anchor stent 100includes a plurality of connector struts 130 affixed to an outermostwire element 105 c on one end, and permanently affixed (such as via aweld or other securement means) to a proximal guidewire 135 at anattachment zone 140 at an opposite end. The proximal guidewire 135 maybe formed with any one of a variety of diameters that may range from0.008 in. to 0.040 in., and may be provided in any one of a variety oflengths that may range from 90 cm to 350 cm. In use, the anchor stent100 provides a means to secure in place the distal end of the guidewire135 to aid in advancing large bore catheters to their intended targetsite distally within tortuous blood vessels and other non-vasculartubular anatomy as further described with reference to FIGS. 2 and 3.

As illustrated in FIG. 1, the anchor stent 100 may include radiopaquemarkers 145 at a distal end 150 thereof. Using fluoroscopy, theradiopaque markers 145 allow an operator to view a position of theanchor stent 100 and to determine whether the anchor stent 100 hasreached a desired treatment site and properly engaged the interior wallof the blood vessels or other lumen. In other embodiments, the wireelements 105 may also (or alternatively) include radiopaque material sothat the periphery/boundary of the stent frame may be viewed.

As mentioned previously, FIGS. 2 and 3 illustrate example embodimentsfor employing the anchor device 10 to guide a catheter through tortuousvessels 155. With reference to FIGS. 2 and 3, the following describesone configuration of the anchor device 10 that may be well-suited foruse in tortuous vessels 155, such as cervical carotid and vertebralarteries. In this configuration, to help ensure that the anchor device10 is able to travel through the tortuous vessel 155 to a target site160, the diameter D_(G) of the proximal guidewire 135 may range frombetween 0.010″ to 0.018″, and have a length L_(G) ranging from between260 cm to 300 cm, and the anchor stent 100 may have a diameter D_(S)ranging between 5 mm to 8 mm. It should be understood that these exampleranges are for illustration purposes only and may be different dependingon the characteristics of the vessel or lumen with which the anchordevice 10 is being employed.

With particular reference to FIG. 2, the anchor stent 100 is introducedand advanced into the target artery 155 via the guidewire 135. Theanchor stent 100 may be introduced (and subsequently retrieved asdescribed below) through a microcatheter 165. In some embodiments, themicrocatheter 165 may have a size 2.3-F to 2.8-F microcatheter, with aninner diameter ranging between 0.021 in. and 0.027 in. The stiffness ofboth the guidewire 135 and the anchor stent 100 help ensure that theanchor stent 100 travels through the artery 155 and to the target site160 with relative ease. Once the anchor stent 100 reaches the targetsite 160, the anchor stent 100 is in a fully expanded condition, withthe wire elements 105 expanding radially outwardly and bearing againstthe interior surfaces of the artery 155 to secure the anchor device 10in position at the target site 160. The radial expansive forces of theanchor stent 100 provide ample resistance to withdrawal of the anchordevice 10, thereby accommodating the introduction of a larger catheter170 that may be used for providing treatment at target site 160 asdescribed below.

In some medical cases, such as for stroke thrombectomy, the anchordevice 10 may be useful for guiding larger catheters 170 throughtortuous vessel 155 while minimizing insertion forces and potentialtrauma. In such embodiments, a tri-axial catheter system 180 inconjunction with the anchor device 10 may allow for the rapidcatheterization of the distal cervical internal carotid artery andvertebral artery required during emergency stroke thrombectomy cases forpatients with difficult tortuous vascular vessel 155. With reference toFIG. 2, the following describes an example procedure for using theanchor device 10 with the tri-axial catheter system 180.

The anchor stent 100 is first introduced to the target site 160 via theguidewire 135 and the microcatheter 165 in a similar fashion asdescribed previously. Once the anchor stent 100 is in position at ornear the target site 160, a second catheter 175 (such as a 5-F catheter)having a larger diameter than the microcatheter 165 is introduced andadvanced toward the target site 160. The second catheter 175 fitsover/around the microcatheter 165 and the guidewire 135, and is guidedto the target site 160 via the microcatheter 165 and the guidewire 135.Finally, the larger catheter 170, which may be 7-8 F balloon-tip guidingcatheter is advanced to its desired vascular position over thepreviously-advanced catheters 165, 175 and the guidewire 135. Once thelarger catheter 170 is in position at the target site 160, the anchordevice 10 may be removed. In some embodiments, the anchor device 10 maybe resheathed by holding the anchor device 10 stationery while advancingthe 2.8 F microcatheter 135 over the anchor device 10. As themicrocatheter 135 is advanced over the anchor device 10, the anchordevice 10 partially or entirely collapses into the microcatheter 135.Thereafter, both the microcatheter 135 (with the anchor device 10) andthe second catheter 175 are removed, leaving the larger catheter 170 inposition at the target site 160 to allow the thrombectomy procedure tomove forward.

FIG. 3 illustrates another example for employing the anchor device 10,such as for cases where it may be difficult to advance a standard 5-Fcatheter (such as catheter 175 of FIG. 2) into the internal carotid orvertebral artery due to markedly tortuous vascular anatomy 185 in anelderly and/or hypertensive patient. With reference to FIG. 3, theinnominate artery, origin of the left common carotid, or origin of theleft subclavian artery may be more easily and rapidly catheterized byintroducing the anchor device 10 (in a similar fashion as described withreference to FIG. 2) with a stiffer 6-F to 7-F distal hook-shaped,coronary-style guiding catheter 190. In one example process, the guidingcatheter 190 is advanced through the artery 185 to a target site (notshown). Thereafter, a suppler microcatheter 195, such as a 2.3-F to2.8-F microcatheter having an inner diameter ranging between 0.021 in.to 0.027 in., is then advanced coaxially through the guiding catheter190 and into the distal target cervical artery 185 (or other vessel)over a guidewire 200. Due to its small size, the microcatheter 200 mayhave a better chance of rapidly navigating tortuous vascular anatomywhile not dislodging the 6-7 F proximal guiding catheter 190. Once themicrocatheter 195 has been advanced to the cervical-petrous junction ofthe ICA or the distal cervical vertebral artery, the guidewire 200 maybe removed and replaced with the anchor device 10 in a similar processas described with reference to FIG. 2.

In some embodiments, a miniaturized version of the anchor device 10 asdescribed with reference to FIGS. 1-3 may allow safer and more rapidintracranial catheter exchanges. This advantage may be due to greaterstability of the distal exchange wire and much lower risk of potentiallyfatal intracranial artery perforations. Such an anchor device 10 may beuseful in coronary artery catheter exchanges and interventions. In otherembodiments, a larger version of the anchor device 10 may be useful forcatheter exchanges in larger caliber vessels, such as the pulmonaryartery, aorta (especially during stent-grafting of abdominal andthoracic aneurysms), and the inferior and superior vena cavae. In stillother embodiments, the anchor device 10 may also be useful innon-vascular endoscopic catheter interventions such as those within thebiliary tree, GI tract, urinary system, and tracheobronchial tree.

FIG. 4 illustrates another embodiment of the anchor stent 100 with aporous barrier 205 that provides a flow passage for blood and othersubstances to allow the anchor device 10 to also function as a filter,such as an inferior vena cava (IVC) filter. With reference to FIG. 4,the anchor stent 100 may include a plurality of connector struts 210that coalesce to form a closed, conical shape at the distal end 150 ofthe anchor stent 100. The porous barrier 205, which may be formed of athin layer 215 of graft material (such as polyurethane or other suitablepolymer), surrounds the distal end 150 of the anchor stent 100. Thebarrier 205 includes a plurality of perforations or pores 220 which maybe of any suitable diameter to filter particles of a desired size. Insome embodiments, the pores/perforations 220 may range in diameter from75 microns to 125 microns. In use, the anchor stent 100 is advanced andpositioned at a target site in a similar fashion as described withreference to FIGS. 1-3. The porous barrier 205 is positioned toaccommodate blood flow through the inferior vena cava, but otherwisetraps thromboemboli from the pelvis and/or lower extremities that couldotherwise cause a fatal pulmonary embolus if it reached the lungs.

FIG. 5 illustrates another embodiment of an anchor device 50 that may beused an embolic device, where the anchor stent 100 may be detachable, oras an antegrade flow occluder to provide a mechanism for infusingtherapeutic particles and/or substances to a target site (not shown) atwhich the anchor device 50 is deployed. With reference to FIG. 5, thedistal end 150 of the anchor stent 100 includes a cap 225 that may bemade of polyurethane or other suitable polymer. Preferably, the cap 225is nonporous, but in some embodiments, the cap 225 may be porous similarto the porous barrier 205 described with reference to FIG. 4. Instead ofa guidewire (such as guidewire 135 in FIG. 1), the anchor device 50includes a flexible hypotube 230 that runs through the stent and extendsoutwardly from the cap 225 at the distal end 150. The flexible hypotube230 accommodates the injection of liquid embolic agents 235, such asn-Butyl cyanoacrylate (NBCA), onyx, or other suitablesubstances/particles for delivery to the target site.

In some embodiments, the anchor device 50 may also include a detachmentzone 240 adjacent the proximal end 245 of the anchor stent 100. Bydetaching the anchor stent 100 at the detachment zone 240, the anchorstent 100 itself (i.e., without the hypotube 230) may be left in thevessel permanently, if desired. In other embodiments, to avoid orminimize potential backflow of the injected agents 235, particularlybackflow of larger particles, the proximal end 245 of the anchor stent100 may include a porous barrier (not shown) similar to porous barrier205 of FIG. 4 to trap the injected agents 235.

FIG. 6 illustrates another embodiment of an anchor device 60 that mayease the advancement of larger catheters up tortuous, atheroscleroticbrachiocephalic vessels, especially in older patients, and particularlyduring endovascular clot retrieval in acute strokes and during carotidstenting procedures. With reference to FIG. 6, the anchor device 60includes a plurality of wire elements 605 coupled together to form ananchor stent 600, which is a generally tubular-shaped, self-expandingmesh structure. Similar to the anchor stent 100 of FIG. 1, the wireelements 605 may be coupled together, such as via a welding process, tocreate a “closed-cell” design with sufficient rigidity to allow theanchor stent 600 to move through tortuous vessels 640, as furtherdescribed with reference to FIGS. 7 and 8.

The anchor stent 600 includes a first stent segment 610 adjacent aproximal end 615, and a second stent segment 620 adjacent a distal end625, the first and second stent segments 610, 620 connected to oneanother via a transition portion 630 to form a continuous anchor stent600 of varying diameter. As illustrated in FIG. 6, the first stentsegment 610 is longer and narrower as compared to the second stentsegment 620. For example, in one embodiment, the length L_(NS) may rangebetween 10 cm and 30 cm, while the length L_(WS) may range between 2 cmand 4 cm. In addition, the diameter D_(NS) of the first stent segment610 may be approximately one-half of the diameter D_(WS) of the secondstent segment 620. For example, the diameter D_(NS) may be approximately3 mm, while the diameter D_(WS) may be between 6 mm and 7 mm, with thetransition portion 630 gradually tapering/increasing between the end ofthe first stent segment 610 and the beginning of the second stentsegment 620. It should be understood that in other embodiments, othersuitable diameters for D_(NS) and D_(WS) and suitable lengths for L_(NS)and L_(WS) may be used without departing from the principles of thedisclosed subject matter.

FIGS. 7 and 8 illustrate example embodiments for employing the anchordevice 600 to advance a large catheter 640 (e.g., an 8F eV3 Cello or 8FCook Shuttle catheter) through tortuous vessels 645. With reference toFIGS. 7 and 8, the anchor stent 600 and guidewire 635 are advancedthrough the vessel 645 (in a similar fashion as described previouslywith reference to the anchor device 10 of FIGS. 1-3) until the widerstent segment 620 reaches a target site 650. At the target site 650, thewider stent segment 620 is in a fully expanded condition, with the wireelements 605 expanding radially outwardly and bearing against theinterior surfaces of the vessel 645 to secure the anchor stent 600 inposition at the target site 650. Thereafter, the catheter 640 isadvanced over the guidewire 635 and the longer, narrow stent segment 610toward the target site 650. As the catheter 640 advances over the narrowstent segment 610, the narrow stent segment 610 collapses inside thecatheter 640. As illustrated in FIG. 8, the longer, narrow stent segment610 portion (with a stent design that promotes axial force transmission)maintains the catheter 640 generally centered within the vessel 645 andaway from the vessel interior wall, thereby simplify the catheterizationprocess. In this manner, the longer, narrow stent segment 610 obviatesthe need for a central catheter or dilator for the delivery of the largecatheter 640.

It is intended that subject matter disclosed in any one portion hereincan be combined with the subject matter of one or more other portionsherein as long as such combinations are not mutually exclusive orinoperable. In addition, many variations, enhancements and modificationsof the concepts described herein are possible.

The terms and descriptions used above are set forth by way ofillustration only and are not meant as limitations. Those skilled in theart will recognize that many variations can be made to the details ofthe above-described embodiments without departing from the underlyingprinciples of the invention.

1. An anchor device for use with catheters, the anchor devicecomprising: an anchor stent formed from a plurality of wire elements,each wire element in the plurality of wire elements having a zig-zagpattern shape, wherein at least one end of a first wire element in theplurality of wire elements is attached to at least one end of a secondwire element adjacent to the first wire element, and wherein the anchorstent further includes a first expandable stent segment having a firstexpanded width, and a second expandable stent segment having a secondexpanded width different from the first expanded width; a plurality ofconnector struts, each connector strut having a first end attached toone of the wire elements of the anchor stent, and an opposite second endcoalescing to form a strut tip; and a guide device attached to theanchor stent at the strut tip.
 2. The anchor device of claim 1, whereinthe first expandable stent segment has a first length and the secondexpandable stent segment has a second length different from the firstlength.
 3. The anchor device of claim 1, further comprising a transitionramp between the first expandable stent segment and the secondexpandable stent segment.
 4. The anchor device of claim 3, wherein thestrut tip is formed adjacent a proximal end of the first expandablestrut segment.
 5. The anchor device of claim 4, wherein the secondexpandable stent segment of the anchor stent includes a radiopaquemarker.
 6. The anchor device of claim 1, wherein a distal end of theanchor stent opposite the strut tip includes a radiopaque marker.
 7. Theanchor device of claim 1, further comprising a porous barrier attachedto a distal end of the anchor stent opposite the strut tip, the porousbarrier composed of a graft material having a plurality of pores formedthereon.
 8. The anchor device of claim 1, further comprising: a barrierattached to a distal end of the anchor stent opposite the strut tip; andwherein the guide device is a hypotube extending through the strut tipof the anchor stent and outwardly through the barrier.
 9. The anchordevice of claim 8, further comprising a porous barrier attached to theanchor stent and surrounding a portion of the hypotube at the strut tip,the porous barrier composed of a graft material having a plurality ofpores formed thereon.
 10. A delivery system, comprising: an expandableanchor stent attached to a guidewire, the expandable anchor stent formedfrom a plurality of wire elements, each wire element in the plurality ofwire elements having a zig-zag pattern shape, wherein at least one endof a first wire element in the plurality of wire elements is attached toat least one end of a second wire element adjacent to the first wireelement; a first catheter having a first diameter, the catheterconfigured to receive the expandable anchor stent and advance theexpandable anchor stent to a target treatment site; and a secondcatheter having a second diameter greater than the first diameter of thefirst catheter, the second catheter configured to fit around the firstcatheter in a telescoping configuration, the second catheter beingmovable toward the target treatment site around the first catheter. 11.The delivery system of claim 10, wherein the expandable anchor stentfurther includes a first expandable stent segment having a firstexpanded width, and a second expandable stent segment having a secondexpanded width different from the first expanded width.
 12. The deliverysystem of claim 11, wherein the first expandable stent segment has afirst length and the second expandable stent segment has a second lengthdifferent from the first length.
 13. The delivery system of claim 11,further comprising a transition ramp between the first expandable stentsegment and the second expandable stent segment.
 14. The delivery systemof claim 10, wherein the expandable anchor stent further comprises aplurality of connector struts, each connector strut having a first endattached to one of the wire elements of the expandable anchor stent, andan opposite second end coalescing to form a strut tip, and wherein thestrut tip attaches the guidewire the expandable anchor stent.
 15. Thedelivery system of claim 14, wherein the strut tip is formed adjacent aproximal end of the first expandable strut segment.
 16. The deliverysystem of claim 14, wherein at least one of the second expandable stentsegment of the expandable anchor stent and a distal end of theexpandable anchor stent opposite the strut tip includes a radiopaquemarker.
 17. The delivery system of claim 14, further comprising a porousbarrier attached to a distal end of the expandable anchor stent oppositethe strut tip, the porous barrier comprising a graft material having aplurality of pores formed thereon.
 18. The delivery system of claim 14,further comprising: a barrier attached to a distal end of the expandableanchor stent opposite the strut tip; and wherein the guidewire comprisesa hypotube extending through the strut tip of the expandable anchorstent and outwardly through the barrier.
 19. The delivery system ofclaim 18, further comprising a porous barrier attached to the expandableanchor stent and surrounding a portion of the hypotube at the strut tip,the porous barrier composed of a graft material having a plurality ofpores formed thereon.
 20. A wire anchor for an anatomical lumen,comprising: a wire; an anchor including: a first expandable segmentcomprising, when expanded, a first diameter; a second expandable segmentcomprising, when expanded, a second diameter, wherein the seconddiameter is different than the first diameter; and a transition segmentthat, when the first expandable segment and the second expandablesegment are expanded, ramps between the first diameter and the seconddiameter; and connector means to attach the second expandable segment tothe wire.